Liao Jie, Yang Lan
Department of Electrical & Systems Engineering, Washington University in St. Louis, MO 63130, St. Louis, USA.
Department of Physics, Washington University in St. Louis, MO 63130, St. Louis, USA.
Light Sci Appl. 2021 Feb 5;10(1):32. doi: 10.1038/s41377-021-00472-2.
Temperature is one of the most fundamental physical properties to characterize various physical, chemical, and biological processes. Even a slight change in temperature could have an impact on the status or dynamics of a system. Thus, there is a great need for high-precision and large-dynamic-range temperature measurements. Conventional temperature sensors encounter difficulties in high-precision thermal sensing on the submicron scale. Recently, optical whispering-gallery mode (WGM) sensors have shown promise for many sensing applications, such as thermal sensing, magnetic detection, and biosensing. However, despite their superior sensitivity, the conventional sensing method for WGM resonators relies on tracking the changes in a single mode, which limits the dynamic range constrained by the laser source that has to be fine-tuned in a timely manner to follow the selected mode during the measurement. Moreover, we cannot derive the actual temperature from the spectrum directly but rather derive a relative temperature change. Here, we demonstrate an optical WGM barcode technique involving simultaneous monitoring of the patterns of multiple modes that can provide a direct temperature readout from the spectrum. The measurement relies on the patterns of multiple modes in the WGM spectrum instead of the changes of a particular mode. It can provide us with more information than the single-mode spectrum, such as the precise measurement of actual temperatures. Leveraging the high sensitivity of WGMs and eliminating the need to monitor particular modes, this work lays the foundation for developing a high-performance temperature sensor with not only superior sensitivity but also a broad dynamic range.
温度是表征各种物理、化学和生物过程的最基本物理特性之一。即使温度有轻微变化，也可能对系统的状态或动态产生影响。因此，对高精度和大动态范围的温度测量有很大需求。传统温度传感器在亚微米尺度的高精度热传感方面遇到困难。最近，光学回音壁模式（WGM）传感器在许多传感应用中显示出前景，如热传感、磁检测和生物传感。然而，尽管其具有卓越的灵敏度，但WGM谐振器的传统传感方法依赖于跟踪单一模式的变化，这限制了动态范围，该范围受激光源的限制，在测量过程中必须及时对其进行微调以跟踪所选模式。此外，我们不能直接从光谱中得出实际温度，而只能得出相对温度变化。在此，我们展示了一种光学WGM条形码技术，该技术涉及同时监测多个模式的图案，可从光谱中直接读出温度。该测量依赖于WGM光谱中多个模式的图案，而非特定模式的变化。它能为我们提供比单模光谱更多的信息，比如实际温度的精确测量。利用WGM的高灵敏度并消除监测特定模式的需求，这项工作为开发一种不仅具有卓越灵敏度而且具有宽动态范围的高性能温度传感器奠定了基础。
